This invention relates to induction heating apparatus, and particularly to such apparatus comprising a pair of opposed coil assemblies between which a workpiece to be heated is moved.
With such apparatus the workpiece, for example a metal strip, is heated by the currents induced therein by the passage of electric currents through the windings of the coil assemblies.
A difficulty which arises with such apparatus is the obtaining of a required temperature profile, for example a uniform temperature, across the width of the workpiece, the width being the dimension of the workpiece perpendicular to the direction of movement of the workpiece between the coil assemblies.
Various ways of meeting this difficulty have been proposed, including particular arrangements of the windings in the coil assemblies, and/or suitable control of the currents supplied to the windings.
A further difficulty which arises is providing an apparatus which can provide a required temperature profile across the width of any workpiece having a width within a predetermined range of widths.